Cutting mechanism for sewing machines



Feb. 24, 1931. H; c., FlsCHER 1,794,282

CUTTING MECHANISM FOR SEWING MACHINES Filed April 20, 1923 5 lShee'os-Sheec, 1

livi- H. C. FISCHER Fea 24, 193i.

CUTTING MECHANISM FOR SEWING MACHINES Filed April 20, 1925 5 Sheets-Sheet 2fv Feb. 24, 1931. Hc. FISCHER 'CUTTING MEQHANISM FOR SEWING MACHINES Filed I'April 20, 1925 5A Sheets-Sheet 4 H. C. FISCHER Feb. 24, 1931.

CUTTING MECHANISM FOR SEWING MACHINES Filed April 20, 1923 5 Sheets-Sheet 5 Patented Feb. `24, 1931 UNITED STATES PATENT oFFicE HERMANN CHRISTIAN FISCHER, OF VIENA, AUSTRIA, ASSIGNR T THE FIRM:

UNION-SPECIAL-MASGHINENFABRIK GESELLSCHAFT MIT BESCHRANKTER HAF- TUNG, 0F STUTTGART, GERMANY- CUTTING MncHAmsM ron SEWING amarilla-Es Application led April 20, 1923, Serial No. 633,539, and in Germany January 23, 1922.

5 being to receive the sewing thread which is countersunk thereinto in order to be protected against wear.

In the devices of this kind hitherto in use, the cutter is stationary and performs the cut,-

ting while the leather is fed forward, whereby the feeding of the leather is rendered diiiicult, and even made impossible if particularly hard leather is being treated.

This drawback is obviated, in accordance ywith my invention, by causing the incisions to be made while the leather i's at rest, that is to say, in the intervals between the feeding movements.

My invention further relates to the means for raising and depressing the upper layer of the leather severed by-the incision. Heretofore the cutting and raising has been effected by meansof a cutter in which the horizontal part of the blade and the vertical edge for raising the upper layer were located in the same vertical plane which rendered the raising of the leather diicult, the width of this layer being further reduced by compression, so that after depression the upper layer would not fully cover the bottom layer. In

the cutting mechanism according to the pres- `ent invention, the raising edge of the cutter is disposed considerably to the rear of the cutting edge, whereby a reduction in width of the raised layer is prevented.

On the other hand, the depressing of the uppeilayer'was hitherto eifected by means of a folding led e which was fixed in relation to the needle an not exchangeable, involving 40 the drawback that the iiap on being folded down was liable to buckle if the cutting width ofthe blade was altered. In -the new cutting mechanism according to the present invention, the folding ledge isexchangeable, anda ledge of suitable width may be inserted for every cutting widthand this ledgecan fury ther be adjusted into the suitable distance with respect to the needle.

In orderto be able to get over projecting "5to parts of the leather, the cutting mechanism nisrn is lowered again into is detachably connected with the sole of the presser foot so that it can be lifted temporarily from the working position and does no more engage the leather, whereas the machine continues sewing until the cutting mechaits former position.

In the drawings affixed to this specification and forming part thereof, two modifications of a device embodying my invention are illustrated diagrammatically by way of example. In the drawings Figure 1 is a plan of the cutting mechanism in combination withthe presser foot and attached to the machine table,

Figure 2 is a plan, partly in horizontal section and drawn to a larger scale.

Figure 3 is a vertical section on the line `b in Figure 1.

Figure 4 shows the cutter in five different positions (a b c d e).

Figure 5 is a front view.

Figure is a vertical section on the line `c--c in Fi ure 7.

Figure Fi re 5.

igure 8 is a vertical section of the parts.

is a side View corresponding to eoy shown in the central Aportion of Figure 7 the plane of section ertending parallel to i the plane of Figure 7.

`Figure 9l is a side viewof theneedle, the L is a section on the line d--d in Figure 16 is a section on the line f--f i Figure 14. Fi 're-17 is a front view of the raising mem r, and

Figure 18 is a side view thereof.A A Figure 19 is a section on the line g-g Figure 17, and

Figure 20 is a plan. 5 Figure 21 is a section on the line lbf-72. in

Figure 19. f

Figure 22 is a perspective view of said member.'

Referring first to Figs. 1 to 12, lthe cutter block 1, in which a` reciprocating cutter bar 2 is carried in a sleeve 1c, is provided with a vertical sleeve 1d adapted to receive the end of a presser bar 3. A spring 23 is inserted in the sleeve 1d and the hollow end of the bar 3 and tends to hold the cutter block 1 down on the sole 24 of the presser foot. A slotted extension 1a of the cutter block 1 engages a second guide bar 4 so as to prevent the cutter block 1 from turning about the bar 3. a 2o A clamp 5 with a screw 8 is secured on the l front end of the reciprocating cutter bar 2 in which the chuck 7, 9 for the cutter 10 is held by means of a pin 6. The chuck supports a finger or depressing member 33. This 25 finger or depressing member holds the work down on the work support and prevents the cutter from penetrating too deeply into the latter and also provides that incisions of uniform depth be obtained.

vA bracket'll is secured on the rear end of the reciprocating cutter bar 2 and. connected with a slide 12 the front end of which is guided in a slot 13 of the cutter block 1. ,A sleeve 14 is free to turn on thecylindrical rear portion of the slide 12, but held against faxial displacement. A pin 14a-is'secured to. the sleeve 14 and connected with the feed lmechanism 17 by a ball and socket joint l15 which is linked to an arm 16a Aprojecting 4o from the feed mechanism 17 by. a pin ,16, as

will'be seen in Fig. 6. j

In the position of parts shown in end elevation in Fig. 74 and, on a largerscale and viewed from the rear in Fig. 7, in Fig. 9, the feed dog 17 a of the Vfeed mechanism 17 has been lowered by the feed cam 17 b and is ready to start for its return stroke. Its return stroke is the working stroke of the cutter 10. In the position shown in Fig. 9, the cutter 10 is immediately in front of the needle 18. Onv the return stroke of the feed mechanism, it is moved to the left for the length of one stitch into its final position shown in dot and dash lines. During this stroke of the cutter, the work 19 remains stationary and the out# ter makes a slit in the work. At the same time, the flap which has been raised by the cutter tothe rear of the needle 18 is folded down by. a folder 2O which is secured to the sleeve 1c of the .cutter block 1 by a clamp 21 and a screw 22. The folder 20 is exchangeable so that the machine may be ada ted to variations in the widthof .the slit. Sefore I the feed mechanism starts on its Working stroke, the needle 18 is raised and the Work is vedge 10c commences to raise t engaged by the feed dog 17a and moved to the right in Fig. 9 forthe length of one stitch. During the feed stroke, the cutter 10 and the folder 20 move with the work and assist the action of the feed dog 17a, the work being engaged from above and below as in a pair of tongs. i

On one side of the presser foot 24 there is provided the lug 25 bearing a stepped screw 26 carrying a lever 27 with a cam face 27a. The sleeve 1d of the' block 1 is provided with a pin 28 located above this curve. l

If the lever 27 is turned upwards by its handle 29, the cam face 27a lifts the pin 28` with its guide hub 1d and alon with them the cutting mechanism connecte therewith. The cutter block 1 can be lifted notwithstanding its connection with the feed mechanism 17 as the ball and socket joint 15 is free to turn on the slide 12 with its sleeve 14. .The sole 24 of the presser foot remains on the work 19. Sewing may now be roceeded with without any cutting, the cutting mechanism being lifted, as described.

The sole 24 of the presser foot carries s. 50 vertical pin 30 connected by ,anarm 31 with the presser bar at the hub 31a.

If the bar 3is lifted by the lever 32, the sole 24 rises with the cutting mechanism so that the finished work is released for lremoval 'and other work. can be placed in position.

. The cutter 10 (Figures 4a, 4b and 4c) essentially consists of the shank 10a extending obliquely in its working position (Figure 4c and serving for attaching the cutter to its holder, and further 'of the horizontal blade 10b. The vertical edge l10c serves for lift,- ing up the severed layer. In order to facilitate'the lifting, the blade 10b is elongated beyond the lifting edge so that the point where the cutter cuts into thealeather lies some distance in front of the-point where the e severed layer which is now sufficiently loose and free at the point of lifting to permit being lifted with but little' pressure and without-being upset.'

The modification illustrated in Figures 13-22 is 'designed especially for work of hard material, such, for instance, as hard and dry kinds of leather. Such work involves the danger that the pressure exerted 'by the cutter acts too strongly on the work and preventsit from beingl securely guided, in connection ,with the possibility that the needle is displaced from its correct position. The severed layer is further liable to become. unequalin thickness and rough, while with very soft leather it tends to become wavy. The usual stationary roller serving as an abutment for the edge of the Work entails vfurther disadvantages, inasmuch as the cutter does not remain exactly in the predetermined seam line. All these disadvantages 'are obviated by the following means.

The cutter bar 2 is again axially displaceL 1'30 able in the block 1 which'can be displaced on the presser bar 3. The pin 6 of the holder 7 carrying the cutter l0 can be clamped fast by means of a screw S at the front end of the cutter vbar in a suitable angular position.

In the sole24 of the presser foot there is inserted the foot plate 45 of the raising meinber 41, the active part of which is connected with the foot plate 45 by a bent arm 44, engages the` slit in the work 19 with a tongue 42 and forms a guide for the needle 18 in the open groove 43 -in order to prevent the needle from'being pressed outwards by the severed layer. Y

The edge ofthe Work 19 is guided by a roller 47 which, however, is not supported in a stationary bearing, but is free to move together with the cutter 10. To this end the roller 47 is adjustably attached to an arm 48 of the cutter holder 7, a clamping screw 49 said needle, a feed mechanism, a cutter bar adapted to reciprocate and operatively connected with said feed mechanism, a sleeve supporting said cutter bar, a cutter capable of cutting at right angles to the reciprocation of the needle and in front thereof, means for securing said cutter to said bar a folding ledge secured to said. sleeve the rear of Said cutter and means adjacent the stitching point engaging the needle for guarding the same and lifting the severed portion ofthe work.

In testimony whereof I aiiix my signature. HERMANN CHRISTIAN FISCHER.

forming the connecting member. Owing to this arrangement the roller 47 always remains in position infront of the place of cutting and does not permit ofthe work giving way during the cutting.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, forcbvious modifications will occur to a person skilled inthe art.

of the work.

2. Cutting mechanism for sewing machines comprising av needle, means for reciprocating said needle, a feedmechanism, a cutter bar adapted to reciprocate and operatively connected with said feed mechanism', a cutter capable of cutting at right angles to the reciprccationof the needle and in front thereof,

means for securing said cutter to said bar,

a linger securedl to said cutter bar in front,

of said cutter andadapted to exert pressure on the work, means above the work for supporting the cutter bar, said means being yieldmgly pressed against the work, and a guide roller carried by the l/cutter bar supporting means and movable up and down therewith for engaging the edge of the work and guiding the same.

3. Cutting mechanism for sewing machines comprising a needle, means for reclprocatmg 

